The existing food processing device applies built-in heater to emit heat for food processing, and the most heater applies electrical heating. The heater is disposed with heating wire; when the heating wire is powered, it generates heat and makes the heater heating up, so as to prepare the food. To achieve that the temperature of the heater is within certain limits, the existing temperature controlling method applies thermal sensor (such as thermistor NTC) built in the heater to real-time sense the temperature of the heater. The microprocessor transmits temperature signal sensed from the thermistor to the food processing device, and the microprocessor will computational analyse the data. If the temperature sensed from the thermistor exceeds the upper limit value of the preset temperature interval, the microprocessor will transmit the control signal to the electrical heating control switch (such as a electrical relay) to cut off the switch. Then the heating wire will stop working, so with the fallen of the temperature of the heater to return to the preset temperature interval. If the temperature sensed from the thermal sensor is lower than the lower limit value of the preset temperature interval, the microprocessor will transmit control signal to the electrical heating control switch to turn on the switch. And the heating wire heats up with the raising of the temperature of the heater to reach to the preset temperature interval.
So the temperature of the heater keeps at a thermostatic range. When the temperature the thermal sensor sensed is within the preset temperature interval, the heater keeps at a thermostatic range by setting a heating period. That is the microprocessor transmitting the on/off control signal to the electrical heating control switch periodically to make the heating wire heating periodically, which makes the temperature of the heater keeps at a thermostatic manner. For example, the working temperature is set at 218° C., the heater will keep at 218° C. after the food processing device is powered unless the food processing device is shut off, whether the food processing device is in use or not. When the food processing device is off used, with the huge difference between the working temperature of the heater and the environment temperature, the abstraction of heat is quick, which results in great energy loose of the empty load (that is in unused status) and energy wasting.